This invention relates to an adhesive for joining containers into cluster packages so as to eliminate the necessity for a plastic ring type carrier. More particularly, this invention relates to a method of joining two or more containers together so as to controllably adhere them together until one or more are removed from the cluster package.
There are many ways to package containers. One way is by the use of cardboard which is wrapped around the periphery of the containers. Cardboard eventually biodegrades but during the time it takes to degrade the cardboard poses a litter problem. Additionally, cardboard cartons are often difficult to open when a container is to be withdrawn from the carton. The cardboard cartons, in addition to being costly, do not permit proper display of the containers. In today's marketplace, merchandising and advertising are extremely important. Decorating the carton sides or edges adds to the time and cost to prepare the package. Moreover, since cardboard is susceptible to moisture, the integrity of the package is reduced or destroyed if the carton becomes wet.
Another way to package containers is illustrated in U.S. Pat. No. 3,446,346, which discloses a method of immersion or dipping of a group of filled containers into molten liquid so that the liquid solidifies on the ends of the containers and encases the ends to form a unitary package. Each container is then removed from the group by breaking apart the solidified plastic between the containers. However, a plastic end remains on each removed container during and after consumption, causing a substantial litter problem. This process of immersion or dipping is time consuming, costly and requires more materials.
Elastic film material has been stretched around containers to contain them, as in U.S. Pat. No. 4,596,330. However, these containers are not packaged to be individually removable one at a time from the package without the package losing its integrity and thus its ability to retain the other containers. This material does not lend itself to high speed article movement along conveyor systems.
The packaging of food and beverage containers into groups is often attempted through the use of plastic ring type can carriers which usually encircle the necks of each container, such as carbonated beverage and beer containers, enabling the removal of one or more cans as desired. See U.S. Pat. No. 4,574,949. These plastic ring type carriers can be an unsightly litter item on beaches, roadsides and parks and can pose an enviromental risk to wildlife who often become entangled in the carriers and die or are injured. In addition, the containers can rotate in the ring or web of the carrier so that the label of each container may not be lined up properly for display on store shelves. Thus, the containers must be rotated by hand in order to reposition the container labels correctly so that the consumer sees an attractive display.
In 1973 and 1975, Adolph Coors Company obtained three U.S. Pat. Nos. 3,759,373, 3,759,378 and 3,902,992, relating to adhesively bonding a multi-container package of cans or bottles together. There is no teaching in any of the three patents of what adhesive could be used for this application. An adhesive which could be used in such an application would have to be capable of hot melt application, be water resistant, be sufficiently strong to maintain the container package intact during normal shipping and handling, be weak enough that the containers may be easily removed from the package by the consumer, be able to maintain strength at room temperature and above and not be brittle at the colder temperatures at which the contents of the containers may be stored. This is an unusual combination of attributes which known adhesives are not required or equipped to achieve.
Thus, it can be seen that there is a need for an adhesive which can be effectively used in the clustering food and/or beverage containers so that the container package is non-littering, efficient, low cost, aesthetically pleasing to the customer, holds the containers in place without rotation, is environmentally desirable and provides the ability to remove each container individually without the package losing its integrity.